Process of separating phosphorus from its phosphate combinations.



n'ovel steps constituting my process as will SAMUEL PEACOGK, OF CHICAGO, ILLINOIS, ASSIGNOR T0 INTERNATIONAL AGRICUL- TURAL CORPORATION, OF NEWYORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OF SEPARATING PHOSPHORU'S FROM ITS PHOSPHATE OOMBINATIO'NS.

No Drawing.

To all whom it may concern Be it known that I, SAMUEL PEAGOCK, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and usebinations while at the same time producing carbids and nitrids of phosphorus which may be utilized in the production of phosphorus oxids, or nitrogen salts at will.

The invention has for its object the attainment of the above, results in a simple, expeditious and comparatively inexpensive manner, and to these ends consists in the be more fully hereinafter disclosed and particularly pointed out in the claims.

I In carrying out my process I finely divide a natural phosphate rock such as the tricalcium phosphate, Ca P,O and mix same with a suitable quantity of finely divided carbo'n such as ground coke, coal dustor other form of fuel carbon. The mixed carbon and phosphate is then heated to a temperature of about 900 C. in an atmosphere containing substantially no free oxygen, when it is found that phosphorus is evolved either as a carbid such as P C or in the form of a vapor. 4 If the reaction is carried out in an atmosphere of nitrogen, free from air, then phosphorus is given off as a nitrid, such as P N or as a carbo-nitrid such as P C T or as a mixture of these two compounds together with some carbid P C and a considerable quantity of free phosphorus, P, in a vaporous form. At'present I am unable to say with certainty whether this free phosphorus is displaced as such or is a decomposition product. It is not probable, however, for various reasons, that free phosphorus would be produced under the conditions stated, and therefore I believe its presence is due to a decomposition of one or more of the above compounds. Whilephosphorus bearing compounds are produced at the temperature and under the conditions stated, the velocity of the reaction is greatly Specification of Letters Patent.

' Patented Feb. 23, 1915.

- Application tiled July 8, 1912. Serial No. 708,276.

increased by raising the temperature to say between 1100 C. and 1300 (3..v Further,

the decomposition of the phosphate is greatly facilitated by maintaining a lowpartial pressure of the products of the reaction. This may be accomplished by carry:

ing out the process in a gas tight furnace through which the mixture-is continuously fed, while nitrogen is admitted at the discharge end and continuously drawn through and out of the furnace at the feed'end; a vacuum pump at the feed end of the furnace being used to maintain the partial pressures atthe desired values. But I pre fer to maintain low partial pressures by simply fl'ushing the furnace at intervals during the process either with nitrogen, or with an inert or neutral gas such as hydrogen, or

even with ordinary fuel or illuminating gas.

I am notas yet able to say with certainty just what atomic linkages are involved in the products actually produced, but from the presence of free :il'losphorus, combined carbon and combined nitrogen (when nitrogen is present in the furnace), and from other considerations, I believe the normal valencies persist, and that the above compounds are the ones produced in the greatest quantities although there may be others present in smaller iioportions. That is to say, the products found in the furnace seem to be limited to he following :carbon monoxid, CO; phosphorus carbid, phosphorus nitrid, P N phosphorus 'carbo-' nitrid, P C N free phosphorus, P; and nitrogen, N. Thefla'st may, of course, be due to an excess of nitrogen present, but I believe at least some of it as well as substantially all of the free phosphorus is due to secondary decompositions. When the temperature is .high and the partial pressures kept low by flushing with nitrogen gas, most of the furnace products are found to be carbon monoxid, CO, an'd 'phosphorus' carbo-nitrid, P C N with some free phosphorus and nitrogen as probable secondary decomposition products.

It will be observed from the foregolng that at the comparatively low temperatures between 900 C. and 1300 C. I am enabled to separate out from its associated compounds the phosphorus in phosphate rock, and to drive it off in the form of a gas or vapor. The gaseous phosphorus compounds,

may then be substantially wholly decomposed by passing. them through fire clay tubes maintained at temperatures of from say 1200 0. to 1400 0., and the free phosphorusrecovered by condensation 'inthe of say not less than two atmospheres, when phosphoric acid usual manner, or the said gaseous compound the following reaction takes place 2r,N +24.H,o:eNH,.H Po,+ NH

On the other hand when the phosphorus carbonitrid, P 0 N is present in suflicient quantity to render the recovery of its combined nitrogen'desirable, it may be likewise pumped into an autoclave, and treated with superheated steam as above, when the fol-.-"'

lowing reaction will take place as i -P1811 0: i

- 2NH4.H2PO;4+8NH3+5002.

In treating the furnace gases with super-v heated steam, any phosphorus carbid, P 0 that might be present will break up as fol- Again, when it is desired to produce phosphorus pentoxid, P 0 only, instead of passing the furnace gases through fire clay tubes for the recovery of free phosphorus as above described,-said gases may be mixed with air in excess, and burned at once to the pentoxid form, when the latter may be recovered as such, or treated with water to produce to form, knowny In ,-t h e step of treating the furnace ases with superheated steam the velocity 0 the Ph P reaction may be controlled by regulating the pressure of the steam. At two atmospheres pressure the reaction velocity is slow; as the pressure and therefore the temperature increases, however, the reaction velocity increases in accordance with well known thermodynamic laws.

It is obvious that those skilled in the art may vary the details of my process without departing from the spirit thereof, and. therefore I do not wish to be limited to the or with water and gases ates in the manner well above disclosure except as may be required 'by the claims.

What I claim is 1. The process of releasing phosphorus from its phosphate combinations and forming a carbid of phosphorus which consists in heating a phosphate in the presence of carbon and in an atmosphere devoid of free oxygen to a temperature above 900 0., substantially as described.

2. The process of releasing phosphorus from its phosphate combinations and forming a carbid of phosphorus which consists in heating aphosphate in the presence of carbon and in an atmosphere devoid of free oxygen to a temperature substantially between 900 0. and 1300 0., substantially as descri ed.

3. he process of releasing phosphorus from its phosphate combinations which consists in heating a phosphate in an atmosphere of nitrogen substantially devoid of free oxygen and in the presence of carbon to a/temperature above 900 0., while reducing below the normal the partial pressures of the reaction products, substantially as 7 described.

4. The process of forming nitrids of phosphorus which consists in heating a natural phosphate mixed with carbon in an atmosphere substantially devoid of free oxygen, and in the presence of free nitrogen, to a temperature substantially between 900? 0. and 1300 0., substantially as described.

5. The processof forming nitrids of phosphorus which consists in heating a natural phere substantiallydevoid of free oxygen, and in the presence of free nitrogen, to a temperature substantially between 900 0. and 1300 0., while substantially maintaining the partial pressures of the reaction products below their normal values, substantially asdescribed.

6. The process of producing fixed nitrogen compounds which consists in heating a mixphosphate mixed with carbon'in an atmos ture of phosphate and carbon in an atmosphere of nitrogen to a temperature sulficient to bring about the reaction; collecting the gases thus produced; and treating them with steam at a temperature sufficient to produce the desired nitrogen compounds, substantially as described.

In testimony whereof, I aflix my signature, in presence of two witnesses.

SAMUEL PEAcocx. Witnesses:

D. S. TOVELL, R. S. Cnnxron. 

